New data on Caucasian weevils from the subgenus Pliadonus Reitter, 1912 of the genus Otiorhynchus Germar, 1822 (Coleoptera: Curculionidae)

New data on the morphology, biology and distribution of Otiorhynchus decoratus Reitter, 1888, O. ciscaucasicus Korotyaev, 1872 and O. osseticus Korotyaev, 1992 are given. Otiorhynchus ciscaucasicus is firstly recorded for Azerbaijan, and O. osseticus Korotyaev, 1992 for Russia. The lectotype of O. decoratus Stierlin, 1877 is designated. The new species Otiorhynchus (Pliadonus) prasolovi Davidian et Arzanov, sp. n. is described from the basin of Jampal River in Abkhazia. This new species is closely related to O. abagoensis Reitter, 1888, from which it differs in the following features: disc of the pronotum is punctured and without granules, the elytral interstriae with row of subrecumbent hairs, the lamella of the aedeagus is triangular.